Seems like many people get this error. I'm using my company's "Team" subscription but we are getting this blocking error. It's not my account it i malay@monaco.co 's license.
Welcome to the community, @John_Tracy! Thanks for reaching out.
This typically means your instance just needs to sync with the Retool licensing servers. You can restart your instance containers in order to force a license check and confirm that this is the root of the issue. If you still see an error after restarting, I'd recommend reaching out to our Support team as they are well-equipped to handle these kind of account and billing questions. 
Gotcha. It's really not ideal for me to need to manually restart containers to initiate a license check intermitently
Hi, I keep running into these errors and cannot use my deployment, Issues like these are extremely detrimental to the ability to use Retool.
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Just to clarify, license checks should happen every ~6 hours or so without needing to restart your containers, but doing so is a pretty foolproof way to diagnose any potential issues. It does sound like the license check isn't going through. Do you know if your instance has limited egress? There are certain allowances that need to be made for outbound traffic on self-hosted instances, as laid out here.
It was a trailing newline in the key from echo <key> | base64. I replaced with echo -n <key> | base64 and that seemed to work.